Integration of Rock Physics and Seismic Attributes for Reservoir Quality Assessment of ‘Solid’ Field, Offshore Niger Delta

Abstract

The decline in the chance of finding commercial quantity of hydrocarbon necessitated the integration of more geophysical tools in order to properly assess the reservoir quality. This study integrated rock physics and seismic attribute to assess the reservoir quality in ‘Solid’ field, offshore Niger Delta. The objectives of this study are to use rock physics analysis to quality check the seismic attribute results and to locate the best productive zones in the field. 3D seismic data and well log data for six wells were used for Formation evaluation, Petrophysical analysis, Structural analysis, Seismic attribute extraction. These results were then checked qualitatively using rock physics analysis. Six sand units (Sand 1, 2, 3, 4, 5 and 6) were correlated across six wells. Petrophysical analysis indicated that the reservoirs have high porosity (20.9% to 25.4%), high permeability (1897 to 2557 mD), high net-to-gross sand (84.7% to 99.0%), and low volume of shale (0.13 to 0.48). This shows that the reservoirs are of good quality. The depth structure map indicates that the reservoirs are mainly fault assisted closures. The seismic attribute extraction for the sand reservoirs shows high amplitude for Sand 1 in areas where wells have been drilled and also in some closures in Sand 2, 3 and 4 which is indicative of hydrocarbon presence. The crossplot of acoustic impedance against shear impedance of Well S5 helped to differentiate sand and shale in the reservoirs. Crossplot of acoustic impedance against Vp/Vs ratio was then used to predict the fluid type in Well S5. The crossplot of acoustic impedance against Vp/Vs ratio of Sand 2 in Well S5 and Sand 1 in Well S4 follows a regular trend with depth. The overall results portrayed that Sand 1, 2, 3 and 4 are of good quality and are oil bearing.